Our HP 4000 has started printing horizontal lines on the right edsge of each printed sheet. The lines are about 1/10″ apart and almost look like gear teeth imprints.
I replaced the tranfer roller and the toner cartridge and got only a slight improvement.
When I slid back the protective door on the old toner cartridge it looked like the white roller had gouge marks about the same spacing as the black bars on the printed sheet.